Grating couplers as key elements in silicon photonic systems have been used to couple optical signals in and/or out of a planar silicon waveguide fabricated on a chip from or to an out-of-plane optical beam. The out-of-plane optical beam may then be coupled to optical fiber communication systems either directly or through a free-space optical system. One-dimensional (1D) grating couplers, formed by silicon rails and trenches, have been used to couple light of a single polarization. In a fiber optical system, the polarization of light in an optical fiber is random; therefore, light of a single-polarization may not be used on a receiver side to couple light from the optical fiber onto a silicon waveguide. Two-dimensional (2D) grating couplers, formed by a 2D post and/or hole array have been used to simultaneously couple light at two polarizations. The structure of the 2D grating coupler may separate two polarizations from the optical signal and forward each into separate waveguides, which may be referred to as polarization splitting. Each of the polarizations in their respective waveguides may then be separately processed before they are forwarded to a single detector. However, 2D grating couplers may have both a lower coupling efficiency of below −3 decibels (dBs) and a lower optical bandwidth than their 1D grating coupler counterparts. Consequently, 2D grating couplers may limit the performance of optical fiber communication systems.